Thermoelectric converter

ABSTRACT

An object of this invention is to provide a thermoelectric apparatus, which is excellent in performance and has sufficiently high thermoelectric conversion ability. 
     Supply means 6,7 for supplying a liquid heat transfer medium 21 against a side of a substrate with N-type semiconductor layers and P-type semiconductor layers supported thereon, said side being opposite to a semiconductor-layer-supporting side of the substrate, is arranged so that the liquid heat transfer medium 21 strikes against the opposite side of the substrate.

TECHNICAL FIELD

This invention relates to a thermoelectric apparatus such asthermoelectric cooling apparatus or thermoionic electricity generator,and especially to a thermoelectric apparatus making use of a fluid, suchas water or antifreeze, as a heat transfer medium therefor.

BACKGROUND ART

FIG. 22 and FIG. 23 are drawings for describing a conventionalthermoelectric apparatus, in which FIG. 22 is a cross-sectional view ofthe thermoelectric apparatus and FIG. 23 is a cross-sectional viewtaking along line X--X of FIG. 22.

As is illustrated in FIG. 22, a group 102 of thermoelectric elements,which are composed of electrodes and P-type and N-type semiconductorlayers, is held between a heat-absorbing-side insulating substrate 100and a heat-dissipating-side insulating substrate 101 both of which aremade of ceramics such as alumina.

A heat-absorbing member 103 carrying heat-absorbing fins or the likeattached thereto is arranged on an outer surface of theheat-absorbing-side insulating substrate 100. On an outer surface of theheat-dissipating-side insulating substrate 101, a flow-passage-formingmember 104 is arranged with openings thereof directed toward thesubstrate 101. Inside the flow-passage-forming member 104, a continuousflow passage is formed so that water 105 as a heat transfer medium isallowed to tortuously flow along the outer surface of the substrate 101from an end of the flow-passage-forming member toward an opposite endthereof. A supply pipe 107 is disposed in the vicinity of the one end ofthe flow-passage-forming member 104, while a drain pipe is arranged inthe vicinity of the opposite end of the flow-passage-forming member.

A predetermined current is fed to the thermoelectric element group 102and, at the same time, the water 105 is caused to flow into theflow-channel-forming member 104 through the supply pipe 107. Heatabsorbed by the heat-absorbing member 103 is transferred to theheat-dissipating-side insulating substrate 101 via theheat-absorbing-side insulating substrate 100 an the thermoelectricelement group 102. By allowing the water 105 to tortuously flow alongthe outer surface of the substrate 101, the water absorbs heat from thesubstrate 101. The water 105 is then discharged out of the systemthrough the drain pipe 108, whereby cooling takes plate on a side of theheat-absorbing member 103.

Its relevant techniques are found, for example, in Japanese LanguageLaid-Open (Kokai) Publication (PCT) No. HEI 6-504361, Japanese PatentApplication Laid-Open (Kokai) No. HEI 5-322366 and Japanese PatentApplication Laid-Open (Kokai) No. HEI 5-343750.

Incidentally, these conventional thermoelectric apparatuses areaccompanied by a problem in that sufficiently high thermoelectricconversion ability is still unavailable from them.

The present inventors have proceeded with an investigation about thisproblem. As a result, it has been found that there is a problemespecially in the manner of allowing a heat transfer medium to flowthrough such thermoelectric apparatuses. Described specifically, it hasbeen found that, because a heat transfer medium is allowed to flowsimply in a tortuous pattern along a surface of an insulating substratein each conventional thermoelectric apparatus, the thermal conductancebetween the heat transfer medium and the insulating substrate is low,thereby failing to obtain any sufficient thermoelectric conversionability.

An object of the present invention is to overcome such a drawback of theconventional art and hence to provide a thermoelectric apparatus whichis excellent in performance and has sufficiently high thermoelectricconversion ability.

DISCLOSURE OF THE INVENTION

To achieve the above object, the invention of claim 1 is characterizedin that supply means, which is provided, for example, with adistributing member or the like, is arranged to supply a liquid heattransfer medium such as water or antifreeze so that the liquid heatmedium strikes, for example, at a substantially right angle, against aside of a substrate carrying N-type semiconductor layers and P-typesemiconductor layers supported thereon and composed, for example, of ametal plate having an electrically insulating thin film thereon, saidside being opposite to a semiconductor-layer-supporting side of thesubstrate.

The invention of claim 2 is characterized in that, in a thermoelectricapparatus according to claim 1, the substrate is a metal substrateprovided on the semiconductor-layer-supporting side thereof with anelectrically insulating thin film.

The invention of claim 3 is characterized in that, in a thermoelectricapparatus according to claim 1, a space extending over substantially anentire area of the substrate is formed on a substrate-opposing side ofthe supply means, and the liquid heat transfer medium which has struckagainst the side of the substrate is allowed to spread within the space.

The invention of claim 4 is characterized in that, in a thermoelectricapparatus according to claim 1, the supply means is provided, on astriking path of the heat transfer medium, with a flattened first space,a plurality of spouting holes, and a flattened second space extendingover substantially an entire area of the substrate so that the firstspace, the spouting holes and the third space are communicated togetherfrom an upstream side toward a downstream side; and the liquid heattransfer medium which has flowed in the first space is spouted in adistributed state toward the side of the opposite substrate through theindividual spouting holes, and the liquid heat transfer medium which hasstruck against the opposite side of the substrate is allowed to spreadwithin the second space.

The invention of claim 5 is characterized in that, in a thermoelectricapparatus according to claim 1, the supply means is constructed so thatthe liquid heat transfer medium strikes against the opposite side of thesubstrate at substantially a right angle.

The invention of claim 6 is characterized in that, in a thermoelectricapparatus according to claim 1, the supply means is provided with anumber of spouting nozzles which extend close to the opposite side ofthe substrate.

The invention of claim 7 is characterized in that, in a thermoelectricapparatus according to claim 1, concavities and convexities againstwhich the liquid heat transfer medium strikes are formed at the oppositeside of the substrate.

The invention of claim 8 is characterized in that, in a thermoelectricapparatus according to claim 7, the concavities and convexities areformed opposite a spouting hole of the supply means.

The invention of claim 9 is characterized in that a substrate, on whichN-type semiconductor layers and P-type semiconductor layers aresupported, and a distributing member, which is provided with a number ofspouting nozzles with spouting holes formed therethrough for spouting aliquid heat transfer medium against a side of the substrate, said sidebeing opposite to a semiconductor-layer-supporting side of thesubstrate, are arranged opposite to each other; and escape recesses arearranged in the vicinity of the spouting nozzles of the distributingmember so that the liquid heat transfer medium spouted against theopposite side of the substrate is allowed to escape from the oppositeside.

The invention of claim 10 is characterized in that, in a thermoelectricapparatus according to claim 9, a number of concavities and convexitiesare formed at the opposite side of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a thermoelectric apparatus according toa first embodiment of the present invention. FIG. 2 is a verticalcross-sectional view of the thermoelectric apparatus. FIG. 3 is across-sectional view taken along line A--A of FIG. 2. FIG. 4 is a planview of a cover member employed in the thermoelectric apparatus. FIG. 5is a cross-sectional view of the cover member. FIG. 6 is a plan view ofa distributing member used in the thermoelectric apparatus. FIG. 7 is across-sectional view taken along line B--B of FIG. 6. FIG. 8 is across-sectional view of a cover member associated with a secondembodiment of the present invention. FIG. 9 is a bottom view of athermoelectric apparatus according to a third embodiment of the presentinvention, in which a part of the thermoelectric apparatus is shown incross-section. FIG. 10 is a bottom view of a thermoelectric apparatusaccording to a fourth embodiment of the present invention, in which apart of the thermoelectric apparatus is shown in cross-section. FIG. 11is a cross-sectional view of a thermoelectric apparatus according to afifth embodiment of the present invention. FIG. 12 is an enlargedfragmentary cross-sectional view of a spouting hole (water supply pipeportion) of a thermoelectric apparatus according to a sixth embodimentof the present invention. FIG. 13 is a plan view of aheat-dissipating-side substrate for use in a thermoelectric apparatusaccording to a seventh embodiment of the present invention. FIG. 14 isan enlarged fragmentary cross-sectional view of theheat-dissipating-side substrate. FIG. 15 is a cross-sectional view ofthe heat-dissipating-side substrate for use in a thermoelectricapparatus according to an eighth embodiment of the present invention.FIG. 16 is a cross-sectional view of a thermoelectric apparatusaccording to a ninth embodiment of the present invention. FIG. 17 is abottom view of a distributing member for use in the thermoelectricapparatus. FIG. 18 is a cross-sectional view of a thermoelectricapparatus according to a tenth embodiment of the present invention. FIG.19 is a plan view of a heat-dissipating-side substrate for use in thethermoelectric apparatus. FIG. 20 is a characteristic diagram showingrelationships between flow rates of water and thermal conductance in thethermoelectric apparatuses according to the ninth and tenth embodimentsof the present invention. FIG. 21 is a characteristic diagram of thermalconductance of the thermoelectric apparatus according to the respectiveembodiments of the present invention and a conventional thermoelectricapparatus. FIG. 22 is a vertical cross-sectional view of theconventional thermoelectric apparatus. FIG. 23 is a cross-sectional viewtaken along line X--X of FIG. 22.

BEST MODES FOR CARRYING OUT THE INVENTION

In each conventional thermoelectric apparatus, a liquid heat transfermedium is allowed to flow along a surface of a base plate (substrate) toeffect a transfer of heat between the base plate and the liquid heattransfer medium. In the present invention, on the other hand, a liquidheat transfer medium is caused to strike against a surface of a baseplate so that the liquid heat transfer medium is ensured to be broughtinto contact with the base plate in a state of a turbulent flow. Thismakes it possible to efficiently conduct a transfer of heat and, as aconsequence, the heat-exchanging ability of the apparatus as whole isincreased.

Before describing the specific embodiments of the present invention, adescription will be made about the present inventors' general finding onimprovements in the performance of such a thermoelectric apparatusmaking use of a heat transfer medium.

As measures for improving the performance of a thermoelectric apparatusof the above-mentioned type, the following approaches and the like canbe mentioned:

[I] To lower the thermal resistance of a substrate, and

[II] To improve the manner of allowing a heat transfer medium to flow.

(i) As means effective for lowering the thermal resistance of asubstrate as the former measure, a metal substrate having an insulatingthin film, like an aluminum substrate provided with a layer of lowthermal resistance, for example, an anodized alumina film may be usedinstead of a conventional insulating substrate made of ceramics such asalumina. Described specifically, an anodized alumina film may be formedon a surface of an aluminum substrate by anodization. As an alternative,aluminum may be thermally sprayed onto a surface of an aluminumsubstrate and may then be converted into an anodized alumina layer.

A problem of reliability however arises if a substrate having athickness as large as a heat-absorbing-side substrate is also used as aheat-dissipating-side substrate, because a metal substrate undergoesexpansion or shrinkage at a much greater rate by heat than a ceramicsubstrate and, due to the resulting thermal stress, the shear stressincreases in the system of theheat-dissipating-side-substrate--heat-dissipating-side electrodes--P,Nsemiconductor layers--heat-absorbing sideelectrodes--heat-absorbing-side substrate.

(ii) To overcome the above-mentioned problem, one of the substrates (forexample, a heat-absorbing-side substrate) may be formed thick likeordinary substrates but the other substrate (for example, aheat-dissipating-side substrate) may be rendered significantly thinnerthan the heat-absorbing-side substrate. In other words, a difference maybe provided in thickness between a heat-dissipating-side substrate and aheat-absorbing-side substrate. This makes it possible to allow theheat-dissipating-side substrate to follow thermal deformations of theheat-absorbing-side substrate, whereby the occurrence of thermal stresscan be reduced in the above-mentioned system.

However, the adoption of the thin substrate involves a potential problemin that the thermal resistance may conversely increase when theoccupation density of the P and N semiconductor layers (the percentageof the sum of cross-sectional areas of the P and N semiconductor layersrelative to the total area of the substrate) is small.

(iii) To cope with this potential problem, it may be contemplated toreduce the increase in thermal resistance when the occupation density ofthe P and N semiconductor layers is small. This can be done byrelatively increasing the area of electrodes and keeping an effectiveheat transfer area while leaving the thin substrate as is.

Concerning the manner of allowing the heat transfer medium to flow, onthe other hand, it is necessary to make an improvement so that, when thethermoelectric apparatus is taken as a whole system, highheat-exchanging ability can be obtained, for example, by supplyingsmaller electric power for moving the medium.

(iv) As a means for obtaining high heat-exchanging ability, it isadvisable to increase the effective heat transfer area by making astructural improvement.

(v) As another means for obtaining high heat-exchanging ability, it mayalso be contemplated to increase the coefficient of heat transfer. Whenthe electric power for moving the medium is maintained constant, it isadvisable to reduce the flow pressure loss of the heat transfer mediumin a flow passage and at the same time, to increase the flow rate of theheat transfer medium, in other words, the quantity of heat to betransferred. The present invention primarily pertains to the technique(v).

The embodiments of the present invention will next be described withreference to the drawings. FIG. 1 is the perspective view of thethermoelectric apparatus which can be used, for example, as athermoelectric cooling apparatus for a refrigerator, freezer, coldstorage or the like, FIG. 2 is the cross-sectional view of thethermoelectric apparatus, FIG. 3 is the cross-sectional view taken alongline A--A of FIG. 2, FIG. 4 and FIG. 5 are the plan view andcross-sectional view of the cover member, respectively, FIG. 6 is a planview of the distributing member, and FIG. 7 is the cross-sectional viewtaken along line B--B of FIG. 6.

As is depicted in FIG. 1 and FIG. 2, the thermoelectric apparatus isconstructed primarily of a heat-absorbing member 1 adapted to bearranged in contact with a cooled side, a heat-absorbing-side substrate2, a thermoelectric element group 3 (see FIG. 2), aheat-dissipating-side substrate 4 (see FIG. 2), a support frame 5, acover member 6, and a distributing member 7 (see FIG. 2).

Although not illustrated in the drawings, the heat-absorbing member 1is, for example, in the form of a container and, if necessary, may beinternally provided with a number of heat-absorbing fins and a fan.

The heat-absorbing-side substrate 2 and the heat-dissipating-sidesubstrate 4 are both made of metal plates such as aluminum plates and,on surfaces in contact with the thermoelectric element group 3, areprovided electrically insulating thin films such as anodized aluminafilms. When insulating films of anodized alumina are formed byanodization, the insulating thin films, without sealing treatment, canexhibit better joinability with the thermoelectric element group 3. Asan alternative, the electrically insulating films can also be formed bythermal spraying or the like.

As is illustrated in FIG. 2, the heat-absorbing-side substrate 2 and theheat-dissipating-side substrate 4 are different in thickness (in thisembodiment, the thickness of the heat-absorbing-side substrate 2: 5 mm,the thickness of the heat-dissipating-side substrate 4: 0.2 mm; there ishence a thickness relationship of the heat-absorbing-side substrate2>the heat-dissipating-side substrate 4), so that the substrate havingthe smaller thickness can sufficiently follow thermal shrinkage (thermalexpansion) of the substrate having the greater thickness. This hasbrought about a reduction in the occurrence of thermal stress in theheat-absorbing-side substrate 2--the thermoelectric element group 3--theheat-dissipating-side substrate 4.

As is well known, the thermoelectric element group 3 is composed ofheat-absorbing-side electrodes, heat-dissipating-side electrodes, and anumber of P-type semiconductor layers and N-type semiconductor layersarranged between both the electrodes, although not illustrated in thedrawings. Structurally and thermally, the P-type semiconductor layersand the N-type semiconductor layers are arranged in parallel with eachother but, electrically, they are connected together in series via theabove-mentioned electrodes. This thermoelectric element group 3 may beof a single-stage structure or of a multistage cascaded structure.

The support frame 5 is molded of a synthetic resin and supports thereonthe heat-dissipating-side substrate 4. It is attached at a basal endthereof to the heat-absorbing-side substrate 2.

The cover member 6 is molded of a synthetic resin and, as is shown inFIG. 5, is integrally provided with a supply pipe 8 and a drain pipe 9both of which extend in a vertical direction. The supply pipe 8 isarranged at a substantially central part of the cover member 6, whilethe drain pipe 9 is disposed adjacent a peripheral edge of the covermember 6. The cover member 6 is provided in a lower half thereof with aperipheral wall 10 which is open downwardly. Inside the peripheral wall,there is formed a space 11 within which the distributing member 7 isarranged.

The distributing member 7 is also molded of a synthetic resin. As isdepicted in FIG. 6, a circular recess 12 is formed approximatelycentrally in an upper surface of the distributing member, and a wallportion 13 is arranged so that the recess is surrounded by the wallportion. The distributing member 7 is provided, on an outer peripherythereof and at a substantially intermediate position as viewed in thedirection of its thickness, with a flange portion 14. Drain holes 15 ofa relatively large diameter are formed in four corners of the flangeportion 14.

Vertically-extending spouting holes 16a-16i are arranged, one at acentral part of the recess 12 and eight at equal intervals at an outerperipheral portion of the recess. The spouting hole 16a at the centralpart has a diameter somewhat greater than the remaining spouting holes16b-16i.

As is shown in FIG. 2, the distributing member 7 has been positionedwithin the cover member 6 by inserting the distributing member 7 intothe cover member 6 and then bonding an upper surface of the wall portion13 of the distributing member 7 to an inner wall of the cover member 6and an outer peripheral surface of the flange portion 14 of thedistributing member 7 to an inner surface of the peripheral wall 10 ofthe cover member 6, respectively. Further, a flattened first space 17 isformed between the inner wall of the cover member 6 and the upper wallof the distributing member 7 and, in communication with the drain pipe9, a drain channel 18 in the form of a square frame is also formed at aposition surrounded by the peripheral wall 10, the wall portion 13 andthe flange portion 14.

By bonding a lower surface of the peripheral wall 10 of the cover member6 to the heat-dissipating-side substrate 4, a flattened narrow secondspace 19 of a height of about 1 to 3 mm is formed between the lower wallof the distributing member 7 and the upper wall of theheat-dissipating-side substrate 4 and, around the flattened secondspace, a collecting channel 20 is also formed in communication with thedrain holes 15 in the four corners.

As is illustrated in FIG. 2, when water 21 is supplied as a heattransfer medium through the central supply pipe 8, the water is allowedto instantaneously spread out within the first space 17 and isvigorously spouted out in a substantially vertical direction toward anupward surface and a plane of the heat-dissipating-side substrate 4through the respective nine spouting holes 16a-16i. The water 21, whichhas struck against the heat-dissipating-side substrate 4 and hasabsorbed heat from the heat-dissipating-side substrate 4, is allowed tospread out within the narrow second space 19, is collected in thesurrounding collecting channel 20, and is then discharged out of thesystem through the drain pipe 9 by way of the nearby drain holes 15 andthe drain channel 18. The water 21 so discharged is cooled in anunillustrated radiator or by self-cooling and is used again through arecirculation system.

FIG. 8 is the drawing which illustrates the second embodiment. In thisembodiment, a drain pipe 9 is arranged at a peripheral wall 10 of acover member 6, and water collected in the collecting channel 20 (seeFIG. 2) is directly discharged through the drain pipe.

FIG. 9 is the drawing which shows the third embodiment. In thisembodiment, a number of pipes 22 are integrally arranged on a lower wallof a distributing member 7. Holes of the pipes 22 serve as spoutingholes 16. Further, spaces between the pipes 22 serve as a collectingchannel 20.

FIG. 10 is the drawing which depicts the fourth embodiment. In thisembodiment, plural slit-like spouting holes 16 are arranged extendingfrom a side of a central part of a distributing member 7 toward asurrounding collecting channel 20.

FIG. 11 is the drawing which illustrates the fifth embodiment. In thisembodiment, a distributing member 7 is composed in combination of anupper member 25, which is provided through a central part thereof with avertically-extending supply pipe 8, and a lower member 26 provided witha drain pipe 9.

Between the upper member 25 and a heat-dissipating substrate 4, aflattened narrow second space 19 is formed, and a collecting channel 20is formed between a raised central portion of the upper member 25 and aninner periphery of the lower member 26.

FIG. 12 is the drawing which shows the sixth embodiment. In each of theabove-described embodiments, the spouting-holes 16 or the supply pipe 8was arranged at a substantially right angle relative to the plane of theheat-dissipating-side substrate 4. In this embodiment, however, spoutingholes 16 or a supply pipe 8 is arranged in a direction inclined relativeto a plane of a heat-dissipating-side substrate 4. Owing to thisinclination, the flowing direction of water 21 is remains unchanged andthe water 21 is allowed to flow smoothly, thereby contributing to areduction in the pressure loss.

FIG. 13 and FIG. 14 are drawings which depict the 9- seventh embodiment.In this embodiment, mounting areas 27 for the thermoelectric elementgroup 3 on the heat-dissipating-side substrate 4 are as four sectionsdivided about a central part of the heat-dissipating-side substrate 4 asa base point, and bent portions 28 of a chevron shape in cross-sectionare formed between the individual mounting areas 27. Each bent portion28 may extend continuously in the form of a rib as shown in the drawingor may be in an interrupted form. Further, the bent portions 29 mayprotrude toward the thermoelectric element group 3 or, conversely,toward a side opposite to the thermoelectric element group 3. Althoughthe bent portions 28 are formed crosswise in this embodiment, a greaternumber of bent portions 28 can be formed.

FIG. 15 is the drawing which shows the eighth embodiment. In thisembodiment, a thin porous thermal conductor 29 having a high rate ofopen area, such as a wire net, an expanded metal or a punching metal, isattached by spot welding or the like to a side of aheat-dissipating-side substrate 4, said side being on a side opposite toa mounting side for the thermoelectric element group 3.

Owing to the formation of the bent portions 28 on theheat-dissipating-side substrate 4 or the attachment of the porousthermal conductor as in the seventh embodiment or the eighth embodiment,a flow of water 21 in the vicinity of the surface of theheat-dissipating-side substrate 4 takes the form of a turbulent flow sothat the heat-absorbing efficiency of the water 21 for theheat-dissipating-side substrate 4 becomes high.

Incidentally, neither the bent portions 28 nor the porous thermalconductor 29 extends to a sealing portion which is formed on and alongthe periphery of the heat-dissipating-side substrate 4.

FIG. 16 and FIG. 17 are drawings which illustrate the ninth embodiment,in which FIG. 16 is the cross-sectional view of the thermoelectricapparatus and FIG. 17 is the bottom view of the distributing member. Asupport frame 5 supports thereon a heat-dissipating-side substrate 4and, on a basal end thereof, is positioned on a heat-absorbing-Bidesubstrate 2 by pins 30 and is fixed there by an adhesive 31.

A cover member 6 is provided with a peripheral wall 10 which is open ina downward direction. Inside the peripheral wall, a distributing member7 is arranged. The peripheral wall 10 is bonded at a lower end thereofto a periphery of the heat-dissipating-side substrate 4 in aliquid-tight fashion with an O-ring 32 interposed therebetween.

From a bottom wall portion 33 of the distributing member 7, manyspouting nozzles 35 having spouting holes 34 therethrough extenddownwards at equal intervals therebetween, and escape recesses 40 areformed around the respective spouting nozzles 35. These escape recesses40 are in communication with each other and are also connected to adrain channel 18. Incidentally, most of the spouting holes 34 andspouting nozzles 35 are omitted in FIG. 17 because the drawing wouldbecome complex if they were all included.

By mounting the distributing member 7 within the cover member 6, thereare formed a flattened first space 17 between the cover member 6 and thedistributing member 7, a flattened second space 19 between thedistributing member 7 and the heat-dissipating-side substrate 4, and adrain channel 18 on an outer side of the distributing member 7. Further,lower ends of the spouting nozzles 35 extend close to the surface of theheat-dissipating-side substrate 4 so that the clearances between thespouting nozzles 35 and the heat-dissipating-side substrate 4 are asnarrow as about 1 to 3 mm or so.

When water 21 is supplied as a heat transfer medium through a centralsupply pipe 8, the water 21 is allowed to instantaneously spread withinthe first space 17 and is vigorously spouted out in a substantiallyvertical direction toward the upper surface and of theheat-dissipating-side substrate 4 through the respective spoutingnozzles 35. The water 21, which has struck against theheat-dissipating-side substrate 4 and has absorbed heat from theheat-dissipating-side substrate 4, immediately moves toward the escaperecesses 40 and separates from the surface of the heat-dissipating-sidebase 4 owing to repulsive force produced as a result of the striking,and fresh water 21 of low temperature then strikes against theheat-dissipating-side substrate 4. This operation is continuouslyrepeated. The water 21 with the heat absorbed therein is collected in adrain channel 18 by way of the escape recesses 40 and is then dischargedout of the system through the drain pipe 9. The water 21 is used againsubsequent to cooling.

Incidentally, the numeral 36 in the drawing indicates reinforcing ribsarranged integrally on the support frame 5, the numeral 37 designates aheat-insulating layer, and the numeral 38 identifies a thin filminterposed between the heat-absorbing-side substrate 2 and thethermoelectric element group 3, having a high thermal conductivity andmade of a filler-mixed silicone resin or the like.

FIG. 18 and FIG. 19 are drawings which depict the tenth embodiment, inwhich FIG. 18 is the cross-sectional view of the thermoelectricapparatus and FIG. 19 is the plan view of the heat-dissipating-sidesubstrate 4. This embodiment is different from the above-described ninthembodiment in that, as is illustrated in FIG. 18, many concavities andconvexities 39 are integrally formed at a surface of theheat-dissipating-side substrate 4 and spouting nozzles 35 of adistributing member 7 are arranged opposite the individual concavitiesand convexities 39. Incidentally, the concavities and the spoutingnozzles 35 arranged opposite thereto are mostly omitted in FIG. 19because the drawing would become complex if they were

Although the concavities are in a form independent from each other inthe concavities and convexities 39 according to this invention, it isalso possible to arrange many groove-shaped concavities and to inserttip portions of plural spouting nozzles 35 into each of thegroove-shaped concavities. Whichever arrangement is selected, the water21 spouted out of the nozzles 35 can effectively absorb heat from theheat-dissipating-side substrate 4 while striking against the concavitiesand convexities 39 and being broken there.

The relationships between the flow rate of the water 21 and thermalconductance in a thermoelectric apparatus (broken line) making use of aheat-dissipating-side substrate 4 a surface of which is flat as shown inFIG. 16 and a thermoelectric apparatus (solid line) making use of aheat-dissipating-side substrate 4 which has many concavities andconvexities 39 on a surface thereof as shown in FIG. 18 are shown inFIG. 20.

In each of the apparatuses, the diameter of spouting holes was set at1.2 mm, the number of the spouting holes was set at 24, and theclearance between, the spouting nozzles 35 and the heat-dissipating-sidesubstrate 4 was set at 2 mm. Further, the thermal conductance hA wasdetermined in accordance with the following formula:

    hA=Q/{T.sub.j -(T.sub.in +T.sub.out)/2}[W/°C.]

where

Q: calorific value: (supplied electric power)

T_(j) : temperature of the substrate

T_(in) : temperature of the water at the inlet

T_(out) : temperature of the water at the outlet

As is clearly envisaged from the diagram, the thermal conductancebecomes higher in both the apparatuses when the flow rate of the water21, which is caused to strike against the heat-dissipating-sidesubstrate 4, is increased. It is understood especially that thethermoelectric apparatus (solid line) making use of theheat-dissipating-side substrate 4 with the many concavities andconvexities 39 arranged at the surface thereof has a higher thermalconductance and is superior in performance.

Although water was used as a heat transfer medium in the above-describedembodiments, the present invention is not limited to the use of water. Aliquid other than water, such as antifreeze, can also be used.

The metal-made substrates were used in each of the above-describedembodiments. This invention is however not limited to the use of suchmetal-made substrates, and ceramics such as alumina, aluminum nitride orthe like can also be used.

In each of the above-described embodiments, the description was madeabout the case that the heat transfer medium was brought into contactwith the heat-dissipating-side substrate. Based on the above-describedembodiments, it is also possible to bring a heat transfer medium intocontact with a heat-absorbing-side substrate.

In each of the above-described embodiments, the description was madeabout the case of the thermoelectric cooling apparatus. However, thepresent invention can also be applied to thermoionic electricitygenerators.

FIG. 21 is the thermal conductance characteristic diagram, in which flowrates (pressure loss ΔP×flow rate G_(w)) of water flowing through athermoelectric apparatus with electric power supplied in a predeterminedquantity to a water feed pump are plotted along the abscissa of thediagram and thermal conductance is plotted along the ordinate. In thediagram, a curve A indicates characteristics of the thermoelectricapparatus according to the present invention shown in FIG. 2, a curve Bcharacteristics of the thermoelectric apparatus according to the presentinvention shown in FIG. 11, a curve C characteristics of thethermoelectric apparatus according to the present invention shown inFIG. 16, a curve D characteristics of the thermoelectric apparatusaccording to the present invention shown in FIG. 18, and a curve Echaracteristics of the conventional thermoelectric apparatus shown inFIG. 22 and FIG. 23.

As is illustrated in FIG. 23, the flow passage of the water 105 in eachconventional thermoelectric apparatus, said flow passage extending fromthe supply pipe 107 to the drain pipe 108, is narrow, and moreover, isbent plural times into a tortuous form and is long. The water 105therefore undergoes a substantial pressure loss. Further, the water 105flows in the state of a substantially laminar flow in parallel with thesurface of the heat-dissipating-side insulating substrate 101. Thetransfer of heat from the heat-dissipating-side insulating substrate 101to the water 105 is therefore not good, so that the thermal conductanceis the smallest as indicated by the curve E.

Compared with the conventional thermoelectric apparatus, thethermoelectric apparatuses according to the respective embodiments ofthe present invention (curves A-D) are each constructed in such way thatthe water 21 is supplied to make it strike against the heat transfersurface of the heat-dissipating-side substrate 4 and also that the flowpassage of the water 21 is shorter in length than that in theconventional thermoelectric apparatus and the pressure loss is small.The thermoelectric apparatus according to each embodiment of the presentinvention therefore has high thermal conductance and excellent thermalconductance characteristics.

Capability of Exploitation in Industry

The present invention is to make a liquid heat transfer medium strikeagainst a surface of a substrate as mentioned above. The liquid heattransfer medium is therefore ensured to be brought into contact with thesubstrate in the state of a turbulent flow, so that an efficienttransfer of heat can take place. As a result, the heat exchangingability of the apparatus as a whole is heightened, thereby permittingexcellent performance.

The use of a metal substrate, which has an electrically insulating thinfilm, as a substrate as described in claim 2 makes it possible tofurther heighten the heat exchanging ability because the metal substratehas extremely low thermal resistance compared with a substrate such asan alumina substrate.

When, as described in claim 3, a space extending over substantially anentire area of the substrate is formed on a substrate-opposing side ofthe supply means and the liquid heat transfer medium which has struckagainst the opposite side of the substrate is allowed to spread withinthe space, the liquid heat transfer medium is allowed to promptly spreadover a wide area in the vicinity of the surface of the substrate.Accordingly, the heat loss is reduced and the heat exchanging ability isheightened.

When, as described in claim 4, the supply means is provided, on astriking path of the heat transfer medium, with a flattened first space,a plurality of spouting holes and a flattened second space extendingover substantially an entire area of the substrate so that the firstspace, the spouting holes and the third space are communicated togetherfrom an upstream side toward a downstream side and, further, the liquidheat transfer medium which has flowed in the first space is spouted in adistributed state toward the opposite side of the substrate through theindividual spouting holes and the liquid heat transfer medium which hasstruck against the side of the substrate is allowed to spread within thesecond space, the distance of the heat transfer medium to the substratecan be shortened and the pressure loss can be reduced, both comparedwith the corresponding distances and pressure losses in the conventionalapparatuses. A still further merit can therefore be brought about inthat the heat exchanging ability is heightened further.

The construction of the supply means so that the liquid heat transfermedium strikes against the opposite side of the substrate atsubstantially a right angle as described in claim 5 makes it possible toperform an efficient transfer of heat by the heat transfer medium.

The provision of the supply means with a number Z' of spouting nozzleswhich extend close to the side of the substrate, said side beingopposite to the semiconductor-layer-supporting side, as described inclaim 6 makes it possible to perform a still more efficient transfer ofheat by the heat transfer medium.

The formation of concavities and convexities, against which the liquidheat transfer medium strikes, at the opposite side of the substrate,said side being opposite to the semiconductor-layer-supporting side, asdescribed in claims 7 and 8 makes it possible to provide athermoelectric apparatus which has high thermal conductance and is moreexcellent in performance as is evident from the results of FIG. 24.

The formation of escape recesses in the vicinity of the spouting nozzlesof the distributing member, said spouting nozzles being adapted to spoutthe liquid heat transfer medium against the substrate, as described inclaims 9 and 10 makes it possible to allow the spent heat transfermedium to promptly escape from the surface of the substrate. Thetransfer of heat is therefore performed efficiently. As a result, theheat exchanging ability of the apparatus as a whole is heightened,thereby permitting excellent performance.

What is claimed is:
 1. A thermoelectric apparatus comprising:a group ofthermoelectric elements having N-type semiconductor layers and P-typesemiconductor layers, a heat-absorbing-side substrate arranged incontact with a side of said group of thermoelectric elements, aheat-dissipating-side substrate arranged in contact with an oppositeside of said group of thermoelectric elements and having a thicknesssmaller than said heat-absorbing-side substrate, a cover member having aspace there inside and provided along a periphery thereof with aperipheral wall, said peripheral wall being closed on an end thereof andbeing open on an opposite end thereof to define an opening, and adistributing member provided with a number of spouting nozzles; whereinsaid opening of said cover member is closed by saidheat-dissipating-side substrate, said distributing member is arrangedinside said peripheral wall of said cover member, whereby said space ofsaid cover member is divided by said distributing member into aflattened first space and a flattened second space and said first spaceand said second space are communicated with each other via said spoutingnozzles of said distributing member; and a liquid heat transfer mediumwhich has been supplied into said first space is allowed to spreadwithin said first space, is distributed to said individual spoutingnozzles and is then spouted toward a surface of saidheat-dissipating-side substrate, said surface being on a side oppositeto a surface of said heat-dissipating-side substrate where saidheat-dissipating-side substrate is maintained in contact with said groupof thermoelectric elements, and said liquid heat transfer medium whichhas struck against said opposite surface is allowed to spread withinsaid second space.
 2. A thermoelectric apparatus according to claim 1,wherein said spouting nozzles of said distributing member are formedsuch that said liquid heat transfer medium strikes against said oppositesurface of said heat-dissipating substrate at substantially a rightangle.
 3. A thermoelectric apparatus according to claim 1, whereinconcavities and convexities against which said liquid heat transfermedium strikes are formed on said opposite surface of saidheat-dissipating-side substrate.
 4. A thermoelectric apparatus accordingto claim 3, wherein said concavities are formed opposite said spoutingnozzles of said distributing member, respectively.
 5. A thermoelectricapparatus according to claim 1, wherein escape recesses are arranged ina vicinity of said spouting nozzles of said distributing member suchthat said liquid heat transfer medium struck against said oppositesurface of said heat-dissipating-side substrate is facilitated to flowaway from said opposite surface of said heat-dissipating-side substrate.6. A thermoelectric apparatus according to claim 1, wherein saiddistributing member is provided with spouting nozzles which extend closeto said opposite surface of said heat-dissipating-side substrate.
 7. Athermoelectric apparatus according to claim 6, wherein concavities andconvexities against which said liquid heat transfer medium strikes areformed on said opposite surface of said heat-dissipating-side substrate.8. A thermoelectric apparatus according to claim 6, wherein escaperecesses are arranged in a vicinity of said spouting nozzles ofdistributing member such that said liquid heat transfer medium struckagainst said opposite surface of said heat-dissipating-side substrate isfacilitated to flow away from said opposite surface of saidheat-dissipating-side substrate.